Juana Lopez Member

Juana Lopez Member Stratigraphic range: Turonian
Unit of	Carlile Formation
Underlies	Niobrara Formation
Overlies	Codel Sandstone member of the Carlile
Thickness	0–6 feet (0.0–1.8 m)
Lithology
Primary	Sandstone with abundant carbonate fossil grains
Other	Gravel, Codel fragments
Location
Country	United States
Type section
Named for	Mesita Juana Lopez Grant, six miles northwest of Los Cerrillos, New Mexico
Named by	Rankin
Year defined	1944

Juana Lopez refers to both the uppermost member of the Carlile Shale formation and to the environment that cause it to form. This unit is calcareous sandstone of Turonian age, Upper/Late Cretaceous series in the southern and western Colorado and northern and central New Mexico.^[1]

Where present, the Juana Lopez is "the most enigmatic" member of the Carlile Shale. It consists of sand with a large content of indistinguishable grains of fragmented coral, shells (especially inoceramid prisms), sharks teeth, bone, etc. It smells of sulfur when freshly broken. It formed on wide, shallow marine shelf, with strong wave action, but with little sediment coming in from land. It was exposed on the land surface between the retreat of the Greenhorn cycle and the advance of the Niobrara cycle of the Western Interior Seaway.^[1]

References